There’s no way around it. Photovoltaics, while incredibly energy efficient, are expensive. In sharp contrast, dye-based solar cells seem to be a cheaper alternative to traditional solar cells. Looking especially promising are tandem cells made up of a conventional n-type and a p-type dye-sensitive solar cell.
P-type cells are different than traditional n-type dye sensitive cells. The p-type cells process is reversed from the standard n-type process. A photocathode contains a special dye and a p-type semiconductor.
The dye, activated by light, pulls electrons out of the valence band of a p-type semiconductor, which transfers “electron holes”—positive charges, (putting the p in p-type) from the dye. Then, the redox mediator takes the electrons from the dye and hands them over to the counter electrode.
Scientists have determined combining both an n-type and a p-type dye-sensitized solar cell to create a tandem cell may be the way to proceed.
However, the process needs more work because the performance of the p-type cells is still lower than the n-type. Researchers from Monash University and the Commonwealth Scientific and Industrial Research Organization (Australia), and University of Ulm (Germany) have determined that using a different redox mediator may improve performance significantly.
The redox potential is signification lower and devices have an energy efficiency of 1.3% while previous systems only had a maximum of 0.41%.
Time will tell if the p-type dye-sensitized solar cell with cobalt-based redox mediator really affects the efficiency of solar cells, but if so, it may lead to a completely new way of designing them.